1. Field of the Invention
The present invention relates generally to a parallelism control device applied to dual-shaft system, and more particularly to a parallelism control device, which is assembled with two rotary shafts of the dual-shaft system to help in fixing the parallelism of the rotary shafts and provide torque effect.
2. Description of the Related Art
There are various electronic apparatuses provided with covers or display screens, such as mobile phones, notebooks, PDA, and electronic books. The covers or display screens are pivotally mounted on the electronic apparatuses via pivot pins or rotary shafts, whereby the covers or display screens can be freely rotated and opened/closed under external force.
In order to operate the display module (such as the screen) and/or the apparatus body module of the electronic apparatus in more operation modes and application ranges, a dual-shaft mechanism is provided between the display module and the apparatus body module, whereby the display module and/or the apparatus body module can be operated in different operation modes by different rotational angles.
One end (or so-called pivoted end) of the rotary shaft structure is generally assembled with a torque module composed of multiple gaskets with through holes and recessed/raised locating sections, frictional plates and springs. Two ends of the rotary shafts are respectively fixedly assembled in a case by means of retainer rings or retainer plates. The other end (or so-called fixed end) of the rotary shaft structure is mounted on the apparatus body module and display module of the electronic apparatus. The springs cooperatively store and release energy to rotate and locate the rotary shafts. Basically, the structural design and assembling process of such rotary shaft structure is relatively complicated and the rotary shafts need to provide longer length for assembling with the torque module. Moreover, the recessed/raised locating sections of the gaskets and the frictional plates are subject to wear after a period of operation. This will affect the locating effect.
Also, when a user operates the display module of the apparatus body module to rotate the same, the rotational action force is applied to one end or fixed end of the rotary shaft to make the rotary shaft rotate. In this case, the other end or the pivoted end of the rotary shaft is likely to slightly deflect. As a result, the electronic apparatus can be hardly smoothly rotated and operated.
That is, the fixed end of the rotary shaft serves as a rotational support point of the action force for rotating the electronic apparatus. This will make the other end or the pivoted end of the rotary shaft deflected. As well known by those who are skilled in this field, in order to solve the above problem, it is necessary to assemble the retainer rings and the retainer plates at two ends of the rotary shaft with the rotary shaft and the case at high precision so as to keep the parallelism of the two rotary shafts and solve the problem of deflection of one end of the rotary shaft. Obviously, this will increase the difficulty in assembling and processing and thus increase the manufacturing cost. This is not what we expect.
The conventional pivot pin structures or rotary shaft structures and the relevant connection components thereof have some shortcomings in use and structural design that need to be overcome. It is therefore tried by the applicant to provide a parallelism control device applied to dual-shaft system to eliminate the shortcomings existing in the conventional rotary shaft structure so as to widen the application range. For example, in comparison with the conventional pivot pin structures or rotary shaft structures, the pivot pin or rotary shaft is assembled with the fixing/control device. In response to the rotation of the electronic apparatus, the fixing device can keep the parallelism of the rotary shafts and minimize the possibility of deflection of one end of the rotary shaft. Also, the torque module composed of the gaskets, the frictional plates and the springs is removed. The fixing/control device itself can provide torque effect to simplify the structure and facilitate the assembling process of the pivot pin or rotary shaft structure. Therefore, the length of the rotary shafts can be shortened and it is no more necessary to assemble the components of the rotary shaft structure at high precision.